This is the working version of a geodesic raytracer for black holes I wrote all the way back in 2018 - back then, I tried to emulate rantonels' STARLESS, but I kept working on it on-and-off and produced this result.
MoviTon raytraces photon paths in Kerr spacetime, and can produce 2D and 3D animations of Kerr black holes. it does this by splitting photon trajectories into 6 first-order differential equations which are then solved with the RK4 method. Matplotlib is used to generate the output frames, which are then saved individually. moviepy then combines these frames and converts them into an mp4 video. Axes and their titles can be toggled on and off by rearranging the positions of the setVisible() function lines in RayTracer.py's image() function.
MoviTon, by default, is set to produce videos of both Kerr and 'Newtonian' black holes with accretion disks viewed from different angles - specifically from 0 to 89.5 degrees as the camera pitches. This can all be changed in run.py, and changing it is in fact encouraged. The technical details of how this was achieved is in the attached report.
To run the program, make sure you have the os, platform, sys, numpy, scipy, matplotlib, glob, pillow, and moviepy Python3 packages installed. Make sure you have a C++ compiler as well. To run the entire raytracer, copy the two .py files and the .cpp file to the same directory. In that directory, run python run.py. Now take a break for around half a day - the raytracer computes 10000 photons per frame and 180 frames in total are generated by default. It's advised that you start the raytracer and leave it running overnight. To change the total number of photons computed, modify the radial_photons and axial_photons variables in RayTracer.py.
It is highly encouraged to fork and modify this program to implement multiprocessing, multithreading, and in general speed it up. Python is a slow language, and the majority of this code comes from a time where I was even more of a novice than I currently am in Python and C++.
This package will work on Windows, but you may need to change some file calling paths in RayTracer.py. One set of videos is in the provided folder.
Example output: Kerr Spacetime w/ only visible components (heavily stylized)
